longer draw bar

Submitted: Thursday, Feb 05, 2009 at 10:23
ThreadID: 65717 Views:8388 Replies:12 FollowUps:26
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Hi all just wondering what your thoughts are on getting a 6inch longer draw bar on our caravan we are having built we carry a lot of extras will it make much of a differance to towing thanks in advance Sue
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Reply By: Shaker - Thursday, Feb 05, 2009 at 10:34

Thursday, Feb 05, 2009 at 10:34
Shouldn't make any difference on a caravan, will make it a little easier to reverse though.
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Reply By: Lotzi - Thursday, Feb 05, 2009 at 10:39

Thursday, Feb 05, 2009 at 10:39
G'day Suepajero

It will make a positive difference to both towing and reversing, but, if you are going to add lots of extras, be aware of the added weight to the draw bar/ tow bar.
Talk to the people who are building your van.
Cheers
Lotzi
AnswerID: 347643

Reply By: Member - Mfewster(SA) - Thursday, Feb 05, 2009 at 10:44

Thursday, Feb 05, 2009 at 10:44
It sure does make a difference. A longer towbar is less likely to sway around. ie towing becomes more stable. Backing is also easier.
AnswerID: 347645

Follow Up By: Member - Wayne David (NSW) - Thursday, Feb 05, 2009 at 11:17

Thursday, Feb 05, 2009 at 11:17
Excuse me if I seem extremely thick here.

If longer drawbars are better, then why aren't they made that way?
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Follow Up By: takenbyaliens (QLD member) - Thursday, Feb 05, 2009 at 11:20

Thursday, Feb 05, 2009 at 11:20
So Wayne what do you think is cheaper???
According to modern astronomers, space is finite..a very comforting thought particularly for people who can never remember where they left things

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Follow Up By: Member - Wayne David (NSW) - Thursday, Feb 05, 2009 at 11:36

Thursday, Feb 05, 2009 at 11:36
So it's just a cost saving thing then?

Surely the longer draw bar could/should be an option at time of order.

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Follow Up By: takenbyaliens (QLD member) - Thursday, Feb 05, 2009 at 11:45

Thursday, Feb 05, 2009 at 11:45
I would think most people buy their vans straight out of a yard that sells stock standard versions. I guess if you know what you want is different you have to ask.
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Follow Up By: Richard Kovac - Thursday, Feb 05, 2009 at 22:49

Thursday, Feb 05, 2009 at 22:49
Wayne

Pros and cons

longer = better towing better backing but larger turning circle, the oppercite for shorter.

I have owned a CT since 1983 and allways owned utes then I got a Prado, could not open the rear door because of the gas bottle...

So I made a sliding draw bar long and short..

Image Could Not Be Found

Cheers

Richard
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Reply By: Ray - Thursday, Feb 05, 2009 at 11:44

Thursday, Feb 05, 2009 at 11:44
I rebuilt my box traier a few years ago and extended the draw bar by 18". You would be amazed at the differance it made. I got the idea when a number of haulage companies extended their draw bars on the trailers of their road trains.
AnswerID: 347658

Follow Up By: Member - Wayne David (NSW) - Thursday, Feb 05, 2009 at 11:51

Thursday, Feb 05, 2009 at 11:51
So Ray extended draw bar is all good news? Nothing detremental (apart from the obvious length issue), such as stress on materials?

Does it keep the tow ball weight the same, reduce or increase? I'm thinking that may depend on where the axle is. Hey I'm way out of my depth here.

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Follow Up By: Ray - Thursday, Feb 05, 2009 at 12:04

Thursday, Feb 05, 2009 at 12:04
I would imagine that the draw bar weight would be less with a longer draw bar. It would be like the lever system. The longer the lever the easier to lift. As far as ground clearance is concerned I don't think it would make much difference
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Follow Up By: Member - Roachie (SA) - Friday, Feb 06, 2009 at 17:28

Friday, Feb 06, 2009 at 17:28
Ray, that would depend on whether you used that extra length to load-up heavy gear in front of the main load-carrying space. I hope nobody takes offence at what I am about to say (there's no malice intended).....but I always get an uneasy feeling when I see a Kimberly Camper. They seem to have a long drawbar BUT then they have a huge storage box in it. I would imagine that if that storage box is loaded up with a fridge and a generator or extra fuel/water, then the ball weight on the tow vehicle will be greatly increased.

As others have said, the longer drawbar makes for easier and more stable towing at speed and also for easier reversing (except that if you are trying to reverse into a tight spot where there is limited room in front of you (eg: in some caravan parks where you are expected to reverse 90° but have the constraint of a narrow road frontage etc), then the longer the rig, the more difficult to manourvre.

The downside is reduced "ramp over angle" (ie: the likelihood of the A frame bottoming-out as you go over an obstacle like a speed hump etc). Another slight/possible side effect is when paying for space on (for example) the Abel Tasman ferry to Tassie, they charge you according to the length of your overall rig.

It's all a matter of comprimise.
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Reply By: x - Thursday, Feb 05, 2009 at 11:58

Thursday, Feb 05, 2009 at 11:58
I would imagine ground clearance would be reduced in rough terrain.

Bob
AnswerID: 347662

Follow Up By: Member - Mfewster(SA) - Thursday, Feb 05, 2009 at 12:50

Thursday, Feb 05, 2009 at 12:50
I can't see why it would be.
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Follow Up By: Axel [ the real one ] - Thursday, Feb 05, 2009 at 13:17

Thursday, Feb 05, 2009 at 13:17
Ramp over angle is reduced ,not ground clearance.
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Follow Up By: Member - Mfewster(SA) - Thursday, Feb 05, 2009 at 16:07

Thursday, Feb 05, 2009 at 16:07
Yes, but on further thought, I think the exit angle clearance for the towed vehicle would be better with a longer towbar. This could be significant if towing a caravan because of the longer overhang.. I agree that the ground clearance would be unchanged.
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Follow Up By: x - Thursday, Feb 05, 2009 at 17:43

Thursday, Feb 05, 2009 at 17:43
Axel,

you are right. Thats what I meant. As you go over a hump the draw bar gets closer to the ground the further apart the back wheels and the trailer wheels are. It could be quite important cresting a sand dune.

Bob
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Reply By: GerryP - Thursday, Feb 05, 2009 at 12:49

Thursday, Feb 05, 2009 at 12:49
Hi all,

This is quite interesting... if you shift the wheels back on an existing van, then the ball weight would increase.

However, if you extend the draw bar, thus making the whole unit longer, but at the same time of course extending the distance between the ball and the wheels, it seems the ball weight would decrease due to the leverage effect mentioned earlier. However, the weight on the axle would correspondingly increase.

I would suggest that there shouldn't be any detrimental effects, but do check the ball weight is around the 5 - 10% of the total van weight when loaded.

Cheers
Gerry
AnswerID: 347671

Follow Up By: Member - Mfewster(SA) - Thursday, Feb 05, 2009 at 12:57

Thursday, Feb 05, 2009 at 12:57
I would think that is correct. However the real advantage is the increased towing stability. The difference is quite marked. Can't remember brand names, but some trailer makers do have longer bars as an option. I have a Cape York off road trailer and the bar is considerably longer than most. It is the most stable trailer I have ever towed.
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Follow Up By: Member - Wayne David (NSW) - Friday, Feb 06, 2009 at 12:37

Friday, Feb 06, 2009 at 12:37
Gerry,

Yes it's interesting alright and the way you expressed the moving of wheels backswards versus moving towball forwards was so clear & where I was at before my brain shut down.

Anotheree that I was trying to think about was 'what if' don't actually extend the A frame of the trailer but extend the metal box section that the coupling attached to. (Hope that's clear).

Would this be the same as extending the draw bar of give a different effect?

I am really enjoying reading the comments on here. It's great!
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Follow Up By: GerryP - Friday, Feb 06, 2009 at 17:20

Friday, Feb 06, 2009 at 17:20
Either extending the actual a-frame or just the bit that the coupling is bolted/welded to would achieve the same end result. In effect, what you are doing in both cases is increasing the distance between the wheels and the ball coupling.

I must agree with several others here also, in that doing this does increase stability and towability (is there such a word??) and certainly makes reversing much easier. However, for off-road travel, ramp-over angle is reduced and it can be a pain through steep creek beds.

In summary though, I think the benefits would outweigh the cons unless you are a real serious off-roader.

Cheers
Gerry
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Follow Up By: Member - Mfewster(SA) - Friday, Feb 06, 2009 at 18:57

Friday, Feb 06, 2009 at 18:57
Umm. Still trying to figure this. I agree on the increased plow effect when going over a sharp crest, such as as a dune. I would think the reverse would apply when going down into the bottom of a creek bed, or exiting a creek bed. I think ???? there is reduced chance of the exit angle of the rear of the trailer hitting the ground with a longer draw bar. Going over the crest of the creek bed after a steep slope has the same problem as per a dune.
I also believe the longer drawbar also improves stability under braking, especially on uneven ground.
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FollowupID: 616108

Follow Up By: Member - Wayne David (NSW) - Friday, Feb 06, 2009 at 22:01

Friday, Feb 06, 2009 at 22:01
Gerry let me try that again,

I'm not referring to extending any part of the trailer. Instead increasing the length of the section that fits into the vehicle rear end. Mines a squarish box shape and I have at least 2 lengths to choose from before I lodge the pin a secure it.

Apologies for poor description, wish I knew it's name.

Sorry also if you already get what I'm talking about but with my scenario there's no increase in distance of trailer wheels to coupling. But there is from car to coupling.

Have I confused you enough yet?

I actually tried an experiment towing with this 'what ever it's called' extended to the max. Unfortunately the electrics disconnected as I exited a car park and I just went with the shorter distance. But I was keen to see if it made any difference to reversing.
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FollowupID: 616138

Follow Up By: GerryP - Saturday, Feb 07, 2009 at 11:39

Saturday, Feb 07, 2009 at 11:39
Ahhh, now that's a whole different deal. By extending the actual hitch, which fits into the receiver of your towbar - in other words making your tow ball stick further out behind your car - you're effectively increasing the distance between the back wheels of the vehicle and the ball, while leaving the trailer as-is.

What this will do is cause more leverage effect (due to existing ball weight) on the car and tend to lessen the weight transfer to the front wheels. In the extreme, this would adversely effect the steering and/or braking of the vehicle. You would probably need to go another notch on your weight distribution hitch if you have one, to compensate. I doubt if it will do anything to improve the handling or towing characteristics and reversing may well become harder as well due to the increased radius when turning.

I may be wrong, but off the top of my head, I can't see any purpose in doing this unless it's a boat trailer and you want to get the boat further down the ramp. In fact, I would go as far as to say that the shorter you can keep the towbar hitch, the better.

In summary, extending the a-frame or coupling section on the trailer, as previously discussed, is good, while sticking the towball further out from the back of the car is not so good.

Cheers
Gerry
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Follow Up By: Member - Wayne David (NSW) - Saturday, Feb 07, 2009 at 14:20

Saturday, Feb 07, 2009 at 14:20
GerryP

Thanks for both your patience, your much appreciated opinion and your well worded explanation.

Blimey for a while there I thought I would never get myself explained. And not knowing the terminolgy didn't help either. So thanks for that.

Okay well based on what you've said, I'll now drop an experiment that I was thinking of conducting around my property by using the extended hitch, without the need for electrics.

With me more often than not it's the reversing that's my problem and the longer draw bar is clearly the solution there.

Cheers
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FollowupID: 616239

Reply By: Member - Norm C (QLD) - Thursday, Feb 05, 2009 at 13:52

Thursday, Feb 05, 2009 at 13:52
Most top end vans that are built to order have an extended draw bar as a standard option.

On my previous CT, I had the draw bar extended about 18 inches (during manufacture). My new Kedron has a 'longer than most' draw bar as standard.

The biggest advantages in my view are:

-far easier to reverse, particularly into tight spots
-better able to carry stuff on the draw bar (within the limits of ball weight)
-more space between vehicle and van for rear opening doors on tow vehicle, etc.
-better towing stability

Subject the the manufacturer's engineering expertise and what they say, and how long the standard bar is, I'd be considering adding more than 6 inches.

Norm C

AnswerID: 347677

Reply By: Member - Graham H (QLD) - Thursday, Feb 05, 2009 at 19:20

Thursday, Feb 05, 2009 at 19:20
Coming from NZ I am amazed at the short drawbars on trailers built here. They are far too short.

At home they all have longer drawbars so as to make the distance between the cars rear axle and the trailer axle longer than the wheelbase of the towing vehicle.

This allows you to turn inside the traliers turning circle when reversing and therefore makes it much easier to keep it straight.

Makes perfect sense but whats up with the manufacturers.

Does cost come before safety and good sense.




AnswerID: 347717

Reply By: Boobook2 - Thursday, Feb 05, 2009 at 20:07

Thursday, Feb 05, 2009 at 20:07
As per above there are lots of advantages with the ramp over angle being the major disadvantage.

BUT make sure you go one size up in the frame. Ie if it is 5" standard get 6" as there is a bigger bending moment force. This adds to weight and price.
AnswerID: 347727

Reply By: Gazza11 - Friday, Feb 06, 2009 at 10:09

Friday, Feb 06, 2009 at 10:09
It will increase the down load on the tow ball particularly if you load up the drawbar with extra stuff.

You may want to consider moving the axle forward by about one third the amount of the extension to keep the rig ballanced.

Alternatively when loading the rig place some heavier stuff towards the rear, in any case if it's a custom build rig you need to get some engineering advice on what towball weight to aim for.
Gazza
AnswerID: 347787

Follow Up By: Member - Mfewster(SA) - Friday, Feb 06, 2009 at 11:15

Friday, Feb 06, 2009 at 11:15
I'm thinking about that Gazza. Certainly the tow ball weight will increase if the longer bar is used to carry more on the bar. Certainly, a longer bar allows the axle to be moved forwards a little, but you still want some down pressure rather than balanced weight on the towball. Assuming the axle/wheels act as a fulcrum, wont the longer tow bar have the effect of being a longer lever handle and therefore lower weight? (Up to a point because the weight of the whole trailer, including the tow bar has to be considered and of course a longer towbar will add to the total weight.)
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Reply By: Gazza11 - Friday, Feb 06, 2009 at 11:37

Friday, Feb 06, 2009 at 11:37
I suggest you go to a boat dealership because when they fit a boat to a trailer they have to adjust it to suit the boat motor combo and they do that by sliding the springs along the frame then tighening the u bolts that attach the assembly to the frame.

Therefore they should understand the parameters but I believe you need about 250kgs of downward weight on the towball.

Regards
Gazza
AnswerID: 347806

Follow Up By: Member - Mfewster(SA) - Friday, Feb 06, 2009 at 12:48

Friday, Feb 06, 2009 at 12:48
250kg downwards pressure on a towbar seems an awful lot. Id' have thought maybe 50 to 100max, but I am guessing.
While this is all interesting, the original post made it clear that he was talking about a caravan. In this case, crossing sandunes etc is irrelevant. The key issues therefore are towing stability and towball weight. I don't think there is any doubt that longer draw bars are safer for highway towing
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Follow Up By: Krakka - Friday, Feb 06, 2009 at 13:35

Friday, Feb 06, 2009 at 13:35
Good to see Mfewster pick up on the point of the original post, talking Caravans and highway towing here.
Regards
Krakka
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FollowupID: 616048

Follow Up By: Gazza11 - Friday, Feb 06, 2009 at 15:32

Friday, Feb 06, 2009 at 15:32
Nothing in my response suggested sanddunes or off road use, but the points I made are entirely relevant to either form of usage.

WRT towball wieght I am mistaken. For a 2006 nissan patrol the "towball down weight should not exceed 200kg" however if it is not heavy enough the trailer will start to fishtail behind the car at any sort of speed. You will often see this on the Hyw when somebody has loaded all their stuff on the bed at the back of a van so care is needed to distribute the load when packing.

So I went and checked and the pamper camper is 130kgs and the boat is 90kgs both have longish drawbars and both handle supurbly.

Regards
Gazza
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FollowupID: 616071

Follow Up By: Member - Mfewster(SA) - Friday, Feb 06, 2009 at 15:58

Friday, Feb 06, 2009 at 15:58
Sorry Gazza. Only my first sentence was in response to your post. I was finding the discussion interesting, but the next bit was just a reminder to all that the original post was re a caravan and highway traveling and I felt we had covered that. I was enjoying, and scratching my head considering, the points on related matters re draw bar length and I wasn't even meaning to suggest that we don't continue discussing these further.
Your figures on towball weight and description of what happens if it is too light, or negative, I reckon would be about right. Having towed with long and short draw bars, I'll go with the long draw bar every time.
I think (up to a certain length) a long draw bar actually gives a shorter turning circle as you can turn the tow vehicle further without getting into a jacknife situation. I may be wrong on this. Any other views on this?
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Follow Up By: Krakka - Friday, Feb 06, 2009 at 20:42

Friday, Feb 06, 2009 at 20:42
I meant to post a reply, sorry Gazza, my follow up wasn't meant to be an "attack" on anyone, just making a point. Your reply actually is quite relevant in regard to the positioning of the axle/springs relevant to the intended load.
Regards
Krakka
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Follow Up By: Gazza11 - Friday, Feb 06, 2009 at 22:14

Friday, Feb 06, 2009 at 22:14
Guys,

No issue, but i wanted to get the subject up in lights, the engineering is fairly well understood but fairly important, too much download on the towbar shifts the Centre of Gravity (C0G) of the towing vehicle rearward taking the load off the front steering and main braking wheels thus rendering them less effective.

Too little load on the tow bar creates the fishtailling situation by lessening the traction of the rear wheels of the tow vehicle.

My dad always said if you can lift the drawbar of the caravan onto the ball it's far too light and if the back of the car drops more than 2" it's too heavy. He told me lots of other stuff and it has taken me 20 years to understand he was invariably correct on every point, he was one smart old bugger!

Cheers
Gazza
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Reply By: Harb - Friday, Feb 06, 2009 at 22:14

Friday, Feb 06, 2009 at 22:14
ayep, got all that!

LO(Luck)
AnswerID: 347904

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